Field of the Invention
The invention generally relates to gesture recognition, and more particularly, to ultrasound-based methods for touchless gesture recognition and apparatuses using the same.
Description of the Related Art
To an increasing extent, screens are being used as an alternative way for users to interact with portable electronic devices, such as touch books, mobile phones, panel Personal Computers (PCs), media player devices, and gaming devices. In addition to providing a basic display function, a screen further comprises one or more touch sensors for detecting the contact of objects thereon, thereby providing a touch-based User Interface (UI). Generally, the touch-based UI requires minimal training and simplifies device operation with intuitive gestures.
However, there may be situations where direct contact on the touch-based UI is not preferred or not feasible. For example, the user may be holding something in each hand, or both hands of the user are greasy or in gloves, or the portable electronic device may be too far away for the user to comfortably reach the screen, or the screen of the portable electronic device may be too big for a user to conveniently touch its entire surface, or the display surface of the portable electronic device may simply be untouchable, e.g., in the case of a projector display. To solve this problem, most practices propose to introduce one or more optical devices, such as camera devices and infrared sensors, for identifying touchless gestures (i.e., gestures without direct contact on any part of the portable electronic device) according to the captured images.
However, the requirement of additional optical devices may considerably increase the cost of hardware, not to mention that always keeping the optical devices on to detect touchless gestures would be very power consuming, which is a huge disadvantage since the power of a portable electronic device is usually quite limited. Thus, it is desirable to have an alternative way of touchless gesture recognition that is more efficient, at least regarding hardware cost and power consumption.